JPS6258814A - Manufacture of cable connection - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a connection part of a cable, particularly a crosslinked polyethylene insulated vinyl sheathed cable (hereinafter referred to as CV cable).

[Prior art] In general, connecting parts for CV cables are made by forming an insulator on the connecting part of the conductor by winding polyethylene tape or extruding it, then incorporating it into a mold, and cross-linking it under high temperature and high pressure by applying gas pressure. It is manufactured by giving rise to

However, in this case, the temperature of the cable outside the mold also increases due to heat conduction in the cable conductor, which may cause thermal deformation of the cable. Such deformation can significantly reduce the insulation performance and must be prevented.

Conventionally, this cable deformation has been prevented by wrapping a pressure tape or the like around the cable portion where deformation may occur. However, with this method, deformation of some part is unavoidable because it is not possible to maintain a sufficient balance between the cable pressing force inside the mold (mainly gas pressure) and the cable pressing force outside the mold (using the presser tape). . To solve this problem, Utility Model Application No. 50-121292 provided a rubber or elastic cylindrical plastic tube for the insulator part to be cross-linked, fixed both ends of the tube on both ends of the cable, and placed it inside the mold. A method has been proposed in which crosslinking is carried out while applying pressure inside the tube. Although effective, this method does not necessarily completely solve the drawbacks of conventional methods since the pressurized area is largely confined within the mold.

[Means for Solving the Problems] An object of the present invention is to provide a method for manufacturing a connection part that can almost completely prevent deformation of the cable insulation part by extending the pressurized part to the outside of the mold. The goal is to provide the following.

In the present invention, a heat-shrinkable tube made of silicone resin or the like is used, and both ends of the tube are fixed to the mold so that the parts near the ends extend to the outside of the mold, and gas is pressurized from the outside of the tube inside the mold. By doing this, gas pressure is applied to both ends of the cable via the part near the high part of the tube that is outside the mold.

[Function] By doing this, the part near the end of the L-bubble that is outside the mold presses the cable insulator to be pressurized (
This will cause the cable to contract as it expands, making it easier to balance the pressure between the cable body and the connection.

Embodiment J FIG. 1 is a schematic cross-sectional view showing one or two embodiments of the present invention.

In FIG. 1, a heat-shrinkable tube 5 made of silicone resin or the like is coated on a connecting portion 1 formed by winding with tape, etc., and the cable 4 is attached to the outside of the mold 2 during heating of the mold. This tube 5 is folded back at a portion where the temperature is sufficiently low that no deformation occurs. and dupe 5
A cuff ○ is attached on top of the tube 5, and the tube 5 is folded back again to form an airtight structure with the mold 2.

A presser tape 7 is attached to the part of the tube 5 that comes out of the mold 2.
etc. may be arranged to prevent unnecessary tube deformation during pressurization.

In such a state, by injecting N2 gas 3 etc. into the mold 2 and pressurizing it, the pressure is applied not only to the inside of the mold but also to the folded part of the tube outside the mold, which causes the mold to heat up and reach a high temperature. The connecting portion and the surface of the cable, which has a low temperature rise outside the mold, are pressurized with uniform gas pressure. Therefore, the possibility of deformation of the cable due to pressure inside and outside the mold is minimized.

According to the method of the present invention, uniform gas pressure can be applied from the high-temperature area of the connection part to the low-temperature area of the cable body during high-temperature crosslinking, and the deformation that occurs on the surface of the cable is almost completely eliminated. Therefore, the problem of deterioration of insulation performance due to electrode irregularities is solved.

Furthermore, during the crosslinking process, the temperature is naturally higher than the melting point of polyethylene, and the crystalline part of the cable also melts, but as the pressure difference is minimized as mentioned above, no flow occurs in the polyethylene, and therefore the molten crystalline part regenerates. There is no change in density or generation of microvoids during crystallization, and insulation performance can be stabilized.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the invention in detail. 1... Connection part, 2... Mold, 3... Pressurized gas. 4... Cable, 5... Heat shrink tube. 6... Color, 7... Presser tape.

Claims (1)

[Claims] (1) After forming the connection part of the cross-linked polyethylene insulated vinyl re-sheathed cable by tape wrapping or extrusion, set a heat-shrinkable tube made of silicone resin or the like onto the connection part so that both ends protrude outside the mold. A method for producing a cable connection part, in which the connection part is placed in a mold and then gas pressurized, and the connection part and a part of the cable at both ends thereof are crosslinked under the same pressure.